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Endo tips    Better Endo    Endo abstracts    Endo discussions

  Internal bleaching
The opinions and photographs within this web page are not ours. Authors have been credited
for the individual posts where they are. Photos: Courtesy of Marga Ree -
From: Marga Ree
Sent: Saturday, November 19, 2005 2:42 PM
Subject: [roots] Internal bleaching

This 40 year old woman wanted to have done something on the 
yellow discoloration of 2.1. She recalled sustaining a trauma 
when she was 20 years of age, after which the tooth turned 
yellow. No other signs or symptoms. Looking at the rad,
you can see a partial  calcification in the coronal part of 
the canal. At midroot level, a canal is clearly visible, 
although of an irregular shape.

After some troughing I found the original canal, which was 
very narrow to begin with, but which became very wide at 
midroot level. There was profound bleeding upon entering
this part . It felt like a resorption defect. Apical 
foramen gauged with LS # 70, and a dressing of Ca(OH)2.

Sec. session: application of an apical plug of MTA, and in 
the third session I finished the RCT , and placed sodium
perborate which I changed 3 times with time intervals of
2 weeks. Before I make the build-up of composite, I soak 
the access opening in 10% sodium ascorbate for a couple of 
minutes, this acts as a kind of a scavenger, to eliminate 
any residual oxygen, which can affect polymerization of 

Here is an old case, which I treated approx 5 years ago. 
I usually place a barrier of RMGIC of 2 mm on top of the 
filling material (see yellow arrows), and apply this with 
a needle tube. This means that the filling material should
be about 4 mm below the CEJ, so after the barrier of 2 mm 
is placed, there is still 2 mm below the CEJ for the sodium 
perborate to be effective. I change the sodium perborate 
every 2 weeks, if necessary. After having obtained a 
satisfactory result, I remove the remnants of peroxide with 
the application of sodium ascorbate for a couple of minutes, 
see below mentioned abstract. Then the usual acid etching,
priming and bonding for a composite build-up.

Below is a summary of Ben Schein on sodium ascorbate.

  Sodium Ascorbate is a non-acidic form of Vitamin C, a major 
  antioxidant as well   as one of the most important Vitamins 
  required by the Human body on a regular   and ongoing basis 
  may assist in the treatment of colds and flu by reducing the
  severity and duration of symptoms . Sodium Ascorbate is a 
  buffered form of Vitamin   C that consists of 90% Ascorbic 
  Acid bound to 10% Sodium. It is sold in Nutrition   Holistic 
  Vitamin Stores in liquid form. "Nutrition freaks"
  use on   a regular and ongoing basis because they think it 
  assists in the treatment of   colds and flu by reducing the 
  severity and duration of symptoms - Marga

1: J Dent Res. 2002 Jul;81(7):477-81. Reversal of compromised bonding in bleached enamel. Lai SC, Tay FR, Cheung GS, Mak YF, Carvalho RM, Wei SH, Toledano M, Osorio R, Pashley DH. Oxygen inhibits polymerization of resin-based materials. We hypothesized that compromised bonding to bleached enamel can be reversed with sodium ascorbate, an anti-oxidant. Sandblasted human enamel specimens were treated with distilled water (control) and 10% carbamide peroxide gel with or without further treatment with 10% sodium ascorbate. They were bonded with Single Bond (3M-ESPE) or Prime&Bond NT (Dentsply DeTrey) and restored with a composite. Specimens were prepared for microtensile bond testing and transmission electron microscopy after immersion in ammoniacal silver nitrate for nanoleakage evaluation. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (P < 0.001). Resin-enamel interfaces in bleached enamel exhibited more extensive nanoleakage in the form of isolated silver grains and bubble-like silver deposits. Reduction of resin-enamel bond strength in bleached etched enamel is likely to be caused by a delayed release of oxygen that affects the polymerization of resin components. 1: Oper Dent. 2003 Nov-Dec;28(6):825-9. Reversal of dentin bonding to bleached teeth. Kaya AD, Turkun M. Many studies have shown a considerable reduction in enamel bond strength of resin composite restorations when the bonding procedure is carried out immediately after bleaching. These studies claim that a certain waiting period is needed prior to restoration to reach the original bond strength values prior to bleaching. This study determined the effect of anti-oxidant applications on the bond strength values of resin composites to bleached dentin. Ninety human teeth extracted for orthodontic purposes were used in this study. The labial surface of each tooth was ground and flattened until dentin appeared. The polished surfaces were subjected to nine different treatments: 1) bleaching with gel (35% Rembrandt Virtuoso) 2) bleaching with gel + 10% sodium ascorbate (SA); 3) bleaching with gel + 10% butylhydroxyanisole (BHA); 4) bleaching with sol (35% hydrogen peroxide); 5) bleaching with sol + 10% sodium ascorbate; 6) bleaching with sol + 10% BHA; 7) bleaching with gel + immersed in artificial saliva for seven days; 8) bleaching with sol + immersed in artificial saliva for seven days; 9) no treatment. After bonding application, The resin composite in standard dimensions was applied to all specimens. The teeth were stored in distilled water at 37 degrees C for 24 hours and a universal testing machine determined their resistance to shear bond strength. The data was evaluated using ANOVA and Duncan tests. Bond strength in the bleached dentin group significantly decreased compared to the control group. On the other hand, the antioxidant treatment had a reversal effect on the bond strength to dentin. After the bleaching treatment, the 10% sodium ascorbate application was effective in reversing bond strength. In the samples where antioxidant was applied after the bleaching process, bonding strength in dentin tissue was at the same level as those teeth kept in artificial saliva for seven days. J Oral Rehabil. 2004 Dec;31(12):1184-91. Effect of 10% sodium ascorbate on the shear bond strength of composite resin to bleached bovine enamel. Turkun M, Kaya AD. Department of Restorative Dentistry and Endodontics, School of Dentistry, Ege University, Izmir, Turkey. summary The purpose of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with three different concentrations of carbamide peroxide (CP) on the shear bond strength of composite resin to enamel. One hundred flat buccal enamel surfaces obtained from bovine incisors were divided into three bleaching groups of 10, 16 and 22% CP (n = 30) and a control group. Each bleaching group was then divided into three subgroups (n = 10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in the control group were not bleached. After the specimens were bonded with Clearfil SE Bond and Clearfil AP-X, they were thermocycled and tested in shear until failure. Fracture analysis of the bonded enamel surface was performed using scanning electron microscope. The shear bond strength data was subjected to one-way analysis of variance followed by Duncan's multiple range test at a significance level of P < 0.05. Shear bond strength of composite resin to enamel that was bonded immediately after bleaching with 10, 16 and 22% CP was significantly lower than that of unbleached enamel (P < 0.05). For all three bleaching groups, when the antioxidant-treated and delayed bonding (1 week) subgroups were compared with the control group, no statistically significant differences in shear bond strength were noted (P < 0.05). Marga, I thought the whole point of the barrier was to block from the Sodium Perborate to get to the CEJ and cause external resorption. Why do you place a barrier at all, if you let the Perborate into the CEJ (which may be incomplete) ? - Thomas Thomas, To my knowledge, there never has been reported an external root resorption following bleaching with the use of sodium perborate. Secondly, in order to get an esthetic result, you should remove any filling material approx 2 mm below the CEJ, due to the direction of the dentinal tubules. My rationale for placing a barrier is that I want to prevent leakage along the root canal filling, and I usually perform bleaching in the same session as the obturation. But this applies to the use of gp and sealer. You should protect the root filling, because it has not completely set at the time of obturation. I use Resilon nowadays, so maybe it is not necessary at all to use a barrier. I don't know, but I guess it doesn't do any harm either. - Marga 1: J Endod. 1991 Aug;17(8):365-8. Intracoronal isolating barriers: effect of location on root leakage and effectiveness of bleaching agents Costas FL, Wong M. United States Army Dental Activities, Ft. Gordon, SC. The purpose of this study was to evaluate the ability of several intracoronal isolating barrier materials to prevent leakage of a bleaching agent into the roots of teeth and to determine whether placement of the barrier material at the cementoenamel junction or below the cementoenamel junction has an effect on the bleaching results of the crowns. Fifty teeth were stained in vitro, and gutta-percha fillings were placed in the root canals. The experimental isolating barriers were placed at the cementoenamel junction or 2 mm below the cementoenamel junction. A walking bleach of Superoxol and sodium perborate was placed in the pulp chamber for three treatments. The roots of the teeth were evaluated for the presence of root decoloration, and the crowns of the teeth were evaluated for bleaching effect. Findings from this study showed a significant difference between gutta-percha alone and gutta-percha with barrier in preventing root decoloration (p less than 0.05). No significant differences were found between the other experimental groups in preventing root decoloration. Placement of an intracoronal isolating barrier material 2 mm below the cementoenamel junction resulted in a more acceptable esthetic bleaching result of the crowns than did placement of barrier material at the cementoenamel junction. For what it is worth Thomas, I have always done it the way marga presented, although I was never aware of a resorption issue. I did it to protect the fill and to allow for a deeper bleaching to present excess discoloration at the cej. - gary Prof. Rotstein, who was my specialisation director gave us a paper explaining the barrier shouldn't be flat, because the CEJ is higher on the M&D aspects of the roots and the barrier should follow the CEJ. The whole point is to prevent O2 reaching the CEJ and causing resorption. No resorption was reported with Sodium Perborate, but many attributed it to this barrier on the CEJ. I am not sure there can be a problem with Sodium Perborate entering the root filling after it's set (but who knows). Estheticly, for sure it's better to place the Perborate bellow CEJ.- Go figure, Thomas From: Marga Ree To: ROOTS Sent: Friday, February 03, 2006 6:51 PM Subject: [roots] Internal bleaching with sodium perborate I have posted this case earlier, but I wanted to show an example of internal bleaching with the use of sodium perborate, I would not recommend to use hydrogen peroxide in high a concentration, see also my response to Jeremy's post on internal bleaching - Marga

beautiful case and results Marga - Rob I've done this very succesfully for years Rubber dam is mandatory as well as protective eyewear for everyone in the room I make a mix with Amosan powder and Hydrogen peroxide solution The best sources of the H2O2 solutions are hairdressers who usually take deliveries of 30, 60 or 90 vols solutions The strongest you can get is 100 vols (about 33% solution ) but it is very caustic - get your pharmacist to mix it fresh Keep it in a dark brown bottle in the dark, date it and get fresh mix after 6 weeks The peroxide will turn the fat/oils in you skins to soap instantly so wear surgical gloves Failure of treatment can usually be traced to failure to follow all of the above Re storage / disposal / fresh solution I use a cotton pellet then ZnPo4 for sealing the cavity Make sure you only go about 2 to 3mm subgingival in your canal preparation. Have the patient ring you if they experience pain Usually happens because you went deeper than 2 to 3 mm I've had really dark teeth go whiter than the contralateral tooth within 24 hours Hope this helps My father gave me the recipe he did endo for 56 referring dentists - Jeremy Rourke Jeremy, I respectfully disagree with you recommendation to use hydrogen peroxide for internal bleaching procedure, as this agent can have some serious side effects. A safer choice is the use of sodium perborate. A very good review article on this topic has been published in the IEJ of May 2003, I have listed their conclusion below here - Marga Review of the current status of tooth whitening with the walking bleach technique T. Attin, F. Paque¤ , F. Ajam & A . M. Lennon Conclusions Discoloured root-filled teeth can be successfully treated using the walking bleach technique. Bleaching is performed by temporarily placing a mixture of sodiumperborate-( tetrahydrate) and water into the pulp chamber. This mixture releases H2O2 which is able to react with the staining substances. In the case of severe and refractory discolouration, 3% H2O2 could be used instead of water. It is not advisable to use the thermocatalytic methodwith heatingof a 30%H2O2 solution, as this procedure increases the risko f external cervical resorption. For the same reason, 30% H2O2 should also not be used for the walking bleach technique. In order to prevent seepage of H2O2 through dentine, it is necessary to place a dense root filling and an additional cervical seal prior to starting the walking bleach procedure. For long-term success, it seems to be important to restore the access cavity with an adhesive filling, which prevents leakage of bacteria and stains. were close on your citation...but see the one I did... Madison and Walton did the study in Dogs...and I'm sure this review article referenced that. I thought you should know so you get the source. - Joey D Jeremy, The only problem with using this technique is that it's associated with increased resorption. Walton did a study in Dogs that is considered a classic...while the abstract is not quite perfect... they found increased resorption with heat OR superoxide/33% H2O2 J Endod. 1990 Dec;16(12):570-4. Related Articles, Links Cervical root resorption following bleaching of endodontically treated teeth. Madison S, Walton R. University of North Carolina School of Dentistry, Chapel Hill. One year following root canal treatment and internal etching and bleaching of anterior teeth in dogs, the animals were sacrificed and the teeth prepared for stereomicroscopic or light microscopic examination. Evidence of cervical root resorption and ankylosis was noted on several teeth. The bleaching factors associated with the teeth exhibiting resorption were heat with 30% hydrogen peroxide. Resorption was not related to walking bleach or to internal etching alone. - Joey D


Typical molar

Type II palatal


Deep split

Gold onlays

Cerec Onlay

Multiple access

MB root

Cavernous sinus

Apical in DB

Apical lesion

Resorption lacuna

Upper bicuspid

Pulpitis case

Multiple tooth isolation

Interdental molar bone

Dens invaginatus

Periapical healing

Microscope Zeiss

Calcific metamorphosis

Instrumentation protocol

Perforation case

Double curvature

Buccal sinus tract

Buccal swelling

Lingual version


Tooth # 4

Dumbing down of dentistry

Evidence based dentistry

Upper incisor

MB and ML canal


Furcal floor

Trauma case

Broken file cases

Large lesion

Flex post

MTA obturation